单选题 (单选题)All of the following are the measured variables or elements in a three-element system of the boiler water level control except ___.

A、 Steam flow

B、 Drum level

C、 Steam pressure

D、 Feed water flow

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相关试题

单选题 (单选题)The rotating exciter armature is usually mounted on ___.

A、 A special place of the engine room

B、 Outside the generator

C、 Another exciting generator

D、 A hollow shaft extension of the main generator rotor

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单选题 (单选题)The emergency power system does not include __.

A、 Emergency generator unit

B、 Megohm insulation panel

C、 Emergency switchboard

D、 Emergency battery

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单选题 (单选题)Brushless generators are designed to operate without the use of __.

A、 Brushes

B、 Slip rings

C、 Commutators

D、 All of brushes, slip rings and commutators

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单选题 (单选题)The purpose of the commutator and brushes on a DC generator is to ___.

A、 Change AC to DC current

B、 Change DC to AC current

C、 Neutralize armature reaction

D、 Carry current to the outside circuit

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单选题 (单选题)An electrical device which employs a stationary armature and a rotating electromagnetic field is used aboard as a ___.

A、 Magnetic amplifier

B、 Ship’s service alternator

C、 Three-wire DC generator

D、 Saturable core reactor

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单选题 (单选题)The __ is a measure of the phase difference between voltage and current and is expressed as the cosine of phase angle.

A、 Power

B、 Efficiency

C、 Effective power

D、 Power factor

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单选题 (单选题)Voltage regulation can be achieved automatically by __.

A、 Adjusting the level of excitation applied to the alternator field

B、 Adjusting the speed of generator

C、 Adjusting the power output of prime mover

D、 Adjusting the fuel feeding rate of prime mover

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单选题 (单选题)A DC generator is used to supply direct current in order to maintain an AC generator field and is known as a/an ___.

A、 Rotor

B、 Stator

C、 Exciter

D、 Armature

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